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Mineralpedia Details for Andradite

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Andradite

Andradite

A member of the Garnet Group named for J.B. d’Andrada e Silva, a Brazilian mineralogist who was the first to describe a variety of this type of garnet. Andradite is common and widespread, and good material can be found in Italy, Romania, Switzerland, Norway, South Africa, Russia, the United States, and Mexico. Hundreds of other localities ate known. Andradite occurs “in skarns from contact metamorphosed impure limestones or calcic igneous rocks, in chlorite schists and serpentinites, [and] in alkalic igneous rocks, [where there are] then typically titaniferous. Associated minerals include vesuvianite, chlorite, epidote, spinel, calcite, dolomite, and magnetite.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/andradite.pdf

Formula
Ca3Fe3+2(SiO4)3 
Crystal System
Isometric 
Crystal Habit
Crystalline - Coarse, Euhedral Crystals, Massive 
Cleavage
None, None, None 
Luster
Vitreous (Glassy) 
Color
black, yellowish brown, red, greenish yellow, gray 
Streak
white 
Class
Isometric - Hexoctahedral 
Fracture
Conchoidal 
Hardness
6.5-7 
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Mindat
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Andradite from Stanley Butte, Graham Co., Arizona, United States

Andradite
            from Stanley Butte, Graham Co., Arizona, United States

Single, euhedral, reddish brown, lustrous crystals to 6mm.

Dodecahedral crystals to 4mm.

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Andradite from Artinite pit, Clear Creek, San Benito Co., California, United States

Andradite
            from Artinite pit, Clear Creek, San Benito Co., California, United States

Beautiful yellow-brown Andradite variety Topazolite crystals from 2-5mm on all sides of matrix.

The varietal name refers to resemblance of these Garnets to Topaz, which indeed they do have that same nice clear color and adamantine luster.

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Andradite from Sandare, Nioro du Sahel, Mali

Andradite
            from Sandare, Nioro du Sahel, Mali

Deep reddish brown lustrous crystals to 8mm.

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Andradite from San Benito Co., California, United States

Andradite
            from San Benito Co., California, United States

Light green garnet crystals to 5mm.

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Andradite from Nightingale dist., Pershing Co., Nevada, United States

Andradite
            from Nightingale dist., Pershing Co., Nevada, United States

Deep red well-formed garnets to nearly 2cm on quartz with many others.

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Andradite from Chukotskii Mountains, Chukotsky, Russia

Andradite
            from Chukotskii Mountains, Chukotsky, Russia

Green crystals to 4mm.

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